This invention relates to an automated, constrained, repeatable and highly accurate method for performing controlled radiation testing, radiation induced annealing, refractive index alteration, altering photonic material constants and space qualification of nanostructure photonic devices. The invention provides a precise, repeatable and simultaneous method for performing diagnostics and tailoring of photonic material and micron and nanometer structure sized regions via radiation induced color center formation or radiation-induced annealing processes at the device atomic and molecular levels.
Alteration and tailoring and measurement of photonic device parameters include: index of refraction, electrooptic coefficients, propagation constants, coupling coefficients, photoelastic constants, absorption constants, and operational optical wavelengths, and other photonic material parameters which are integral to the operation and function of guiding, modulating, attenuating, amplifying, polarizing, filtering, beam shaping, coupling, or controlling optical signals within photonic circuitry. Photonic circuitry includes optical interconnect technologies and systems comprised of components such as emitting lasers, integrated photo-detector amplifiers (i.e. Si PIN photodiodes and poly Si thin film transistors) and optical integrated receivers using Ga As MESFET and MSM technologies, etc., fiber optic systems and components (optical fibers, fiber amplifiers, fiber grating, demultiplexers, sources and detectors) and other photonic technologies which are susceptible to radiation induced defects or effects, or can be hardened through annealing and/or wherein color centers can be introduced into selected areas, lengths and volumes to alter the transmissive and other optical and electrical properties of the devices.
Photonic devices include, but are not limited to, integrated optical circuits, optical interconnect technologies, opto-electronic integrated optics, thin-film and guided wave devices, and other nanostructure and micro-sized photonic components such as quantum-well laser diodes, injection laser diodes, fiber optics and fiber optic components, PIN photodiodes, charge-coupled devices, charge-injection devices, etc. The disclosed method uses a focused and defocused ion microbeam to accurately pin-point or distribute radiation on discrete volumes, lengths and areas on or within nanostructure devices. Accuracy on the order of 1-2 microns and larger are currently available using several ion beam accelerators and possibly ion beam milling machines which allow highly accurate exposure of photonic technologies for the purpose of irradiating specific nanostructure regions and excluding or isolating surrounding or adjacent regions from exposure. This three-dimensional exposure technique allows limited radiation testing, annealing and alteration of the refractive index (via color-centers) of specific nanostructure regions without the accumulation of total dose over the entire nanostructure regions. This process facilitates cost-effective and constrained survivability, space qualification and hardness testing with delivery of highly accurate dose and dose rates, and lends itself to on site production line testing.
To date, the normal procedure is to use gross radiation exposure using finite sized radiation beams ranging from unapertured 1-2 cm.sup.2 sized beams, located extremely close to the device under test. This arrangement is highly undesirable since proximity between the DUT and output port of the radiation source cause inconveniences in positioning the DUT. In the currently used radiation exposure methods, radiation induced phenomena such as absorption, crosstalk, polarization effects, refractive index changes, etc., cannot be confidently or accurately attributed to the differently composed (doped) regions within these photonic components. This is because the gross size of the radiation beams currently used may overlap two or more regions of the nanometer/micrometer structures which result in compound and complex responses. The aperturing down of these gross dimensional radiation beams effectively reduces the instantaneous dose and dose rates and results in minimizing the radiation doses delivered and the responses being studied. Such aperturing dose not effectively focus the exposure beam and overlapping may again occur, which limits resolution and results in inhomogeneous irradiation of the exposed areas. The method allows alteration of various photonic device physical characteristics via radiation induced color center formation within the material atomic and molecular structure. Thus, tailoring of the photonic material indices of refraction, electrooptic coefficients, photoelectric constants, propagation constants, coupling coefficients, etc. are possible.
The disclosed method avoids these problems and allows the analysis to be performed in a vacuum or partial vacuum or to some extent in air on other gaseous environments. Thus, in vacuum, a space environment can be stimulated and, space qualification procedures can be confidently applied. Also, since the ion microbeam method allows more working space between the DUT and the radiation emission region, thermoelectric coolers and heating devices can be applied readily to the DUT, again allowing additional testing and qualification test procedures to be followed.